A variety of optical devices have one or more waveguides positioned on base. The waveguides often guide light signals to other optical components such as modulators, switches, demultiplexers, and light sensors. These waveguides often receive the light signals from an external second optical device and/or guide the light signals to the external optical device. Accordingly, the light signals are often transferred between a waveguide on the optical device and an external optical device such as an optical fiber.
The mode size for the waveguide is often different than mode size of the external optical device. For instance, the mode size of waveguides on planar optical devices is often smaller than the mode size of the optical fibers with which the planar optical device exchanges light signals. The difference in mode size is a source of optical loss that may limit device performance. In order to address this issue, a taper is often added to the waveguide that exchanges light signals with the second optical device. For instance, the waveguide on a planar optical device can be tapered such that the mode size of a light signal carried in the waveguide expands to the mode size of the optical fiber with which the waveguide will exchange light signals.
Fabrication of a tapered waveguide on an optical device can interfere with fabrication of the other components on the same optical device. The fabrication challenges become even more evident when the taper is both vertical and horizontal. As a result, there is need for a system that permits the exchange of light signals between different optical devices without complicating the fabrication process.